[IPOL announce] new article: Local JPEG Grid Detector via Blocking Artifacts, a Forgery Detection Tool
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Thu May 21 11:19:19 CEST 2020
A new article is available in IPOL: http://www.ipol.im/pub/art/2020/283/
Tina Nikoukhah, Miguel Colom, Jean-Michel Morel, and Rafael Grompone von
Gioi,
Local JPEG Grid Detector via Blocking Artifacts, a Forgery Detection Tool,
Image Processing On Line, 10 (2020), pp. 24–42.
https://doi.org/10.5201/ipol.2020.283
Abstract
Image JPEG compression leaves blocking artifact traces. This paper
describes an algorithm that exploits those traces to locally recover the
grid embedded in the image by the JPEG compression. The algorithm
returns a list of grids associated with different parts of the image.
The method uses Chen and Hsu's cross-difference to reveal the artifacts.
Then, an a contrario validation step according to Desolneux, Moisan and
Morel's theory delivers for each detected grid a Number of False Alarms
(NFA) which tells how unlikely it is that the detection is due to
chance. The only parameter is the step size of the windows used, which
represents the exhaustiveness of the method. The application to image
forgery detection is twofold: first, the presence of discrepant JPEG
grids with low NFA is a strong forgery cue; second, knowledge of the
grid is anyway required for further JPEG forensic analysis.
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